.btna{
    width: 50px;
    height: 30px;
    color: aliceblue;
    border: none;
    border-radius: 4px;
    padding: 3px;
}
/* 个性化特征 */
.btnb{
  
    background-color: brown;
  
}
.btnc{
   
    background-color: brown;
  
}